Virtual image display apparatus

ABSTRACT

In a projection system, a nonaxisymmetric aspheric surface is used as a surface that is located in a position where in a pencil of light of video image light that exits from each of two points in different corner regions in an image plane that is a light exiting plane of an image display apparatus, light components that should reach a viewer&#39;s eyes do not intersect one another, whereby the size of an optical system can be further reduced and the size of an overall apparatus can therefore be reduced with a variety of types of optical precision, such as the resolution and angle of view, maintained.

BACKGROUND

1. Technical Field

The present invention relates to a virtual image display apparatus thatpresents a viewer with video images formed by an image display apparatus(video device).

2. Related Art

There are a variety of proposed optical systems incorporated in avirtual image display apparatus, such as a head mounted display(hereinafter also referred to as HMD) mounted on a viewer's head (seeJP-A-2015-72438, for example).

As a virtual image display apparatus of this type, there is a knownapparatus that achieves reduction in the size of the apparatus with highprecision maintained, for example, by using, as an optical system, alight guide member that has at least two nonaxisymmetric curved surfacesthat guide video image light and forms an intermediate image inside (seeJP-A-2015-72438).

In the field of an HMD and other similar apparatus, it is required toachieve further size reduction with optical precision maintained, and itis desirable that a light guide member and a projection system that formthe optical system of the HMD or any other similar apparatus are soconfigured that the length of the light guide member in the light guidedirection and the overall length of the projection system are furthershortened. However, the total reflection condition for guiding videoimage light in the light guide member, suppression of aberrations, asatisfactory angle of view, a satisfactory eye ring diameter, and avariety of other design conditions restrict the reduction in the size ofthe optical system, for example, by using the configuration described inJP-A-2015-72438.

SUMMARY

An advantage of some aspects of the invention is to provide a virtualimage display apparatus that allows further reduction in the size of anoptical system with optical precision maintained and hence reduction inthe size of the overall apparatus.

A virtual image display apparatus according to an aspect of theinvention includes a video device that generates video image light, alight guide member that guides the video image light from the videodevice based on total reflection that occurs at a plurality of surfacesincluding a nonaxisymmetric curved surface and serves as part of anoptical system to form an intermediate image in the light guide member,and a projection system that causes the video image light from the videodevice to enter the light guide member. The projection system includesat least one nonaxisymmetric aspheric surface, and the onenonaxisymmetric aspheric surface is located in a position where in apencil of light of video image light that exits from each of two pointsin different corner regions of a light exiting plane of the videodevice, light components that should reach a viewer's eyes do notintersect each other.

In the virtual image display apparatus described above, the projectionsystem includes at least one nonaxisymmetric aspheric surface located ina position where in a pencil of light of video image light that exitsfrom each of two points in different corner regions of a light exitingplane of the video device, light components that should reach theviewer's eyes do not intersect each other. Therefore, the size of theoptical system that guides light with an intermediate image formed inthe light guide member can be further reduced and hence the size of theoverall apparatus can be reduced.

In a specific aspect of the invention, the video device generates thevideo image light from a rectangular region, and in the projectionsystem, the one nonaxisymmetric aspheric surface is located in aposition where in a pencil of light of video image light that exits fromeach of four corners of the rectangular region of the video device,light components that should reach the viewer's eyes do not intersecteach other. In this case, the size of the virtual image displayapparatus that allows visual recognition of a rectangular image formedby video image light can be reduced.

In another aspect of the invention, the light guide member has at leasttwo nonaxisymmetric curved surfaces. Among the plurality of surfacesthat form the light guide member, a first surface and a third surfaceare so located as to face each other, and the first surface and thethird surface provide diopter of roughly zero when an outside scene isvisually recognized through the first surface and the third surface. Thevideo image light from the video device is totally reflected off thethird surface, is totally reflected off the first surface, is reflectedoff a second surface, then passes through the first surface, and reachesan observation side. In this case, the size of the apparatus can bereduced with the state of see-through observation, which allowssuperposition of an outside scene on an image formed by the video imagelight and visual recognition of the superimposed image, satisfactorilymaintained.

In still another aspect of the invention, an exit angle of a pencil oflight of the video image light that exits from the video device isasymmetric with respect to a center of the video device. In this case,the optical path is so adjusted as to be further shortened by theasymmetry of the exit angle of the pencil of light of the video imagelight.

In still another aspect of the invention, assuming that a firstdirection is a direction orthogonal to a direction of a normal to thelight exiting plane of the video device and corresponding to a lightguide direction of the light guide member and that a second direction isa direction orthogonal to the direction of the normal and the firstdirection, pencils of light that exit from pixels arranged along thefirst direction in the video device exit at difference angles along thesecond direction. In this case, causing the pencils of light that exitfrom the pixels to exit at different exit angles along the seconddirection allows the optical path of the overall pencils of light to beso adjusted as to further decrease.

In still another aspect of the invention, the projection system has astop that forms an opening that is not only so located as to beorthogonal to a lens optical axis passing through a center of the videodevice and parallel to the direction of the normal but also symmetricwith respect to a first axis that extends in parallel to the firstdirection and intersects the lens optical axis but asymmetric withrespect to a second axis that extends in parallel to the seconddirection and intersects the lens optical axis or an opening that is sodisposed as not to be orthogonal to the lens optical axis. In this case,the stop allows appropriate light adjustment even when the pencils oflight from the pixels of the video device exit at exit angles differentfrom one another along the second direction.

In still another aspect of the invention, each of the pixels of thevideo device is so structured as to spread wider in the second directionthan in the first direction. In this case, occurrence of luminanceunevenness can be suppressed.

In still another aspect of the invention, curvature of the onenonaxisymmetric aspheric surface, which forms the projection system, ineach position where a pencil of light that exits from the video devicepasses changes in correspondence with an incidence angle of the pencilof light, which exits from the video device, at the nonaxisymmetriccurved surface that forms the light guide member.

In still another aspect of the invention, in a pencil of light thatexits from each pixel of the video device, a direction of a light beamhaving highest luminance varies in accordance with a position of thepixel of the video device. In this case, causing the luminance to varyin accordance with the position of a pixel of the video device, that is,adjusting the luminance in advance on the side where the video imagelight is generated allows occurrence of luminance unevenness to besuppressed when the video image light in the form of video imagesreaches the eyes.

In still another aspect of the invention, the video device includes aliquid crystal panel, and an interval in a TFT pixel structure differsfrom an interval in a counter substrate pixel structure having a blackmatrix structure. In this case, in the space between the TFT pixelstructure and the black matrix structure, the range of the light thatpasses through the space and the angle of the light are adjusted, andluminance unevenness and color unevenness are suppressed in each of thepixels, whereby a high-quality image can be formed.

In still another specific aspect of the invention, the video deviceincludes an organic EL panel that has a light emitting layer and a colorfilter layer, and an interval in the light emitting layer differs froman interval in the color filter layer. In this case, using the organicEL panel allows reduction in size and weight of the apparatus and highlyefficient, high-definition image formation. Further, in this case, inthe space between the light emitting layer and the color filter layer,light control on a pixel basis, for example, by adjustment of thearrangement of the color filter layer allows adjustment of the range andangle of the light passing through the space, whereby luminanceunevenness and color unevenness can be suppressed for high-quality imageformation.

In still another aspect of the invention, the video device includes adeflection member that is disposed in a light exiting section disposedon a light exiting side, and the deflection member changes the angle ofthe light. In this case, the deflection member can change the angle ofthe light to suppress luminance unevenness and color unevenness forhigh-quality image formation.

In still another aspect of the invention, the nonaxisymmetric curvedsurface of the light guide member is provided at least on a lightincident section disposed on a light incident side and a light exitingsection disposed on a light exiting side. In this case, the size of thelight guide member can be reduced.

In still another aspect of the invention, in the light guide member, adistance from an intersection of a light incident section disposed on alight incident side and a lens optical axis of the projection system toan intersection of a light exiting section disposed on a light exitingside and a sight line axis assumed to be a reference of the viewer'sline of sight is 48 mm or smaller. In this case, from a viewpoint oflong time use of the apparatus used as an HMD, the exterior appearanceof the apparatus, and other factors, the size of the apparatus can besufficiently reduced.

In still another aspect of the invention, the light guide member has asemi-transmissive/reflective section that partially reflects andtransmits the video image light from the video device and outside light,and the light guide member is connected to a light transmissive membervia the semi-transmissive/reflective section. In this case, the lightguide member cooperates with the light transmissive member to form astructure in which the light guide member and the light transmissivemember sandwich the semi-transmissive/reflective section, whereby theviewer is allowed to not only visually recognize the video image lightbut also visually recognize or view an outside image in see-throughobservation.

In still another aspect of the invention, the light guide member isformed of a pair of right and left light guide members, and the pair ofright and left light guide members and the light transmissive member areso configured that the pair of right and left light guide memberssandwich the light transmissive member and are connected each other viathe light transmissive member to forma unitary optical member. In thiscase, image recognition in binocular vision is allowed, and the lighttransmissive member allows the positioning for the binocular vision tobe readily and precisely performed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a perspective view for briefly describing the exteriorappearance of an example of a virtual image display apparatus accordingto an embodiment.

FIG. 2 is a plan view showing the optical path in a main body portionthat forms the virtual image display apparatus.

FIG. 3 is a side view showing the optical path in the main body portionthat forms the virtual image display apparatus.

FIG. 4 is a perspective view showing the optical path of a projectionsystem.

FIG. 5A is a cross-sectional view showing the configuration of theprojection system, and FIG. 5B is a front view of a lens barrel in theprojection system.

FIG. 6A conceptually shows an example of the arrangement of a videodevice and a stop in the projection system, and FIG. 6B conceptuallyshows a variation of the arrangement of the video device and the stop inthe projection system.

FIG. 7A is a conceptual view showing the periphery of an image displayapparatus having an exemplary configuration, and FIG. 7B is a conceptualview showing a central side of the apparatus.

FIG. 8 is a conceptual view for describing a variation of the imagedisplay apparatus.

FIG. 9 is a conceptual view for describing another variation of theimage display apparatus.

FIG. 10A is a conceptual plan view for describing a variation of a lightguide apparatus, and FIG. 10B is a front view of the light guideapparatus.

FIG. 11A conceptually shows another example of the virtual image displayapparatus, and FIG. 11B conceptually shows still another example of thevirtual image display apparatus.

FIG. 12 is a plan view showing the optical path in a main body sectionin still another example of the virtual image display apparatus.

FIG. 13A is a cross-sectional view showing the configuration of theprojection system according to a variation, and FIG. 13B is a front viewof the lens barrel in the projection system according to the variation.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

A virtual image display apparatus according to an embodiment of theinvention will be described below in detail with reference to FIG. 1 andother figures.

A virtual image display apparatus 100 according to the presentembodiment is not only a head mounted display having a glasses-likeexterior appearance, as shown in FIG. 1, but also a virtual imagedisplay apparatus that allows a viewer or a user on whom the virtualimage display apparatus 100 is mounted to visually recognize image light(video image light) in the form of a virtual image and further allowsthe viewer to visually recognize or view an outside image in see-throughobservation. The virtual image display apparatus 100 includes first andsecond optical members 101 a, 101 b, which cover the front side of theviewer's eyes but allow see-through observation, a frame section 102,which supports the two optical members 101 a and 101 b, and first andsecond image formation main body sections 105 a, 105 b, which are addedto portions extending from the right and left ends of the frame section102 to rear bow portions (temples) 104. A first display apparatus 100A,which is the combination of the first optical member 101 a and the firstimage formation main body section 105 a on the left in FIG. 1, is aportion that forms a virtual image for the right eye, and the firstdisplay apparatus 100A functions as a virtual image display apparatus byitself. Similarly, a second display apparatus 100B, which is thecombination of the second optical member 101 b and the second imageformation main body section 105 b on the right in FIG. 1, is a portionthat forms a virtual image for the left eye, and the second displayapparatus 100B functions as a virtual image display apparatus by itself.Comparison of FIG. 2 with FIG. 1 shows, for example, that each of thefirst and second image formation main body sections 105 a, 105 b isformed of a projection lens 30, which is a projection system, and animage display apparatus 80 (video device), which includes an imagegenerator 81. FIG. 2 shows the display apparatus for the left eye butdoes not show the display apparatus for the right eye, which has thesame structure as that of the display apparatus for the left eye. Inaddition to the components described above, a nose receiver 40, whichcomes into contact with the viewer's nose and therefore plays a role insupporting the frame section 102, is provided.

The display apparatus 100B can be considered to include aprojection/see-through apparatus 70, which is an optical system forprojection, and the image display apparatus 80, which forms video imagelight, as shown in FIG. 2. The projection/see-through apparatus 70includes the second optical member 101 b or a light guide apparatus 20and the projection lens 30 for image formation and plays a role inprojecting an image formed by the image display apparatus 80 in the formof a virtual image onto the viewer's eye. In other words, theprojection/see-through apparatus 70 is not only a virtual image opticalsystem that guides light from an image plane OI, which is a plane fromwhich image light (video image light) formed by the image displayapparatus 80 exits, to allow the viewer to visually recognize a virtualimage but also an image formation optical system that performs imagereformation on the viewer's retina. The second optical member 101 b orthe light guide apparatus 20 is formed of a light guide member 10 forlight guide operation and see-through operation and a light transmissivemember 50 for see-through operation. The second image formation mainbody section 105 b is formed of the image display apparatus 80 and theprojection lens 30. The image plane OI is also a panel planerepresenting the position of a panel that forms the image displayapparatus 80. Further, in a case where the image display apparatus 80 isa self-luminous illuminator, it can also be said that the image plane OIis a light emitting plane.

The optical system described above has several optical axes, and thereference of each of the optical axes is defined as follows: First, thecentral optical axis of the projection lens 30 is called a lens opticalaxis LX; a central axis that extends along the light guide direction ofthe light guide member 10 is called a light guide axis DX, and the lightguide axis DX is an axis that passes through the center of the lightguide member 10, which has a flat-plate shape, and extends along theflat-plate shape; and a central axis that is set on the light exitingside of the light guide member 10 and assumed to be the reference of theviewer's line of sight is called a sight line axis SX. The sight lineaxis SX is an axis extending from the center position of an assumed eyeposition EY, which is assumed to be the eye position, (hereinafter alsosimply described as an eye EY to include a case where an eye is actuallylocated in the assumed eye position EY) toward the center of a lightexiting segment of the light guide member 10. Further, the intersectionof a light incident section (second light guide section 12, which willbe described later) disposed on the light incident side of the lightguide member 10 and the lens optical axis LX of the projection lens 30is called an intersection C1, and the intersection of a light exitingsection (first light guide section 11, which will be described later)disposed on the light exiting side of the light guide member 10 and thesight line axis SX is called an intersection C2. The distance (spacing)indicated by the bidirectional arrow AA in FIG. 2 from the intersectionC1 to the intersection C2 is assumed to be 48 mm or smaller. The sightline axis SX inclines with respect to the lens optical axis LX by about7° (more accurately, 6.7°). The sight line axis SX further inclines byabout 10° with respect to a normal to the light guide axis DX. That is,the sight line axis SX and the light guide axis DX intersect each otherand form an angle of reflection of about 80°. As a result, in the casedescribed above, the lens optical axis LX and the light guide axis DXintersect each other and form an angle of reflection of about 106.7°.

In the image display apparatus 80, the image plane OI is a planeorthogonal to the lens optical axis LX, and the lens optical axis LXpasses through the center of the image plane OI. It is now assumed thatan x direction (direction corresponding to X direction), which is thehorizontal direction in a plane parallel to the image plane OI, iscalled a first direction DD1, and that a y direction (directioncorresponding to Y direction), which is the vertical direction in theplane parallel to the image plane OI, is called a second direction DD2.A z direction is the direction of a normal to the image plane OI and thedirection in which the lens optical axis LX extends. In the presentembodiment, the exit angles of pencils of light of the video image lightthat exits from the image plane OI are asymmetric with respect to thecenter line of the image plane OI (lens optical axis LX) in therightward/leftward direction (x direction), as shown in FIGS. 2 to 4.The exit angles are symmetric with respect to the center of the imageplane OI in the upward/downward direction (y direction) (see FIG. 3).

Referring back to FIG. 2, the image display apparatus 80 includes animage generator 81, which forms the image plane OI that is formed ofpixels arranged in a matrix and serves as a self-luminous illuminatorincluding an organic EL light source (organic EL panel), a lightorientation controller 82, which is disposed in a position immediatelydownstream of the image generator 81 and controls the orientation ofeach light component of video image light GL that exits from the imageplane OI of the image generator 81, and a drive controller (not shown)that controls the action of the image generator 81 and other components.Although will be described later in detail (see FIGS. 7A and 7B andother figures), in the embodiment, a color filter layer CF, which isdisposed in a position immediately downstream of the image generator 81,functions as the light orientation controller 82 to adjust the exitangles of the light components of the video image light GL that exitfrom the periphery of the image plane OI. For example, among sub-pencilsof light of the video image light GL, a sub-pencil of light GLa, whichexits from an inner portion of the image plane OI or a portion thereofrelatively close to the viewer's body (viewer), and a sub-pencil oflight GLb, which exits from an outer portion of the image plane OI or aportion thereof relatively far away from the viewer's body, exit atdifferent exit angles. It is assumed that in the pencil of light thatforms the video image light GL, the sub-pencils of light GLa and GLbmean light components that should reach the viewer's eye.

The projection lens 30 is a projection system that projects the videoimage light GL having exited from the image display apparatus 80 towardthe light guide apparatus 20. In the present embodiment, in particular,a lens having an aspheric surface having a nonaxisymmetric shape(nonaxisymmetric aspheric surface or free-curved form surface) isdisposed on the side close to the image display apparatus 80 to allowreduction in the size of the overall optical system.

The light guide apparatus 20 is formed of the light guide member 10 forlight guide operation and see-through operation and the lighttransmissive member 50 for see-through operation, as described above.The light guide member 10 is part of the prism-shaped light guideapparatus 20 and is a member integrated therewith, but can be consideredas the combination of a first light guide section 11 (light exitingsection) on the light exiting side and a second light guide section 12(light incident section) on the light incident side. The lighttransmissive member 50 is a member that assists the light guide member10 in performing the see-through function (assistant optical block) andis integrated with and fixed to the light guide member 10 to form thesingle light guide apparatus 20.

The role of the projection/see-through apparatus 70, which is a virtualimage optical system, that is, the light guide apparatus 20 and theprojection lens 30 will be described below in detail with reference toFIG. 2.

The projection lens 30 is an optical system that allows the video imagelight GL to be incident from the image display apparatus 80 and projectsthe video image light GL and is a projection system including, asconstituent elements, three optical elements (first to third lenses) 31to 33 along the lens optical axis LX. The optical elements 31 to 33 areeach formed of an aspheric lens having an aspheric surface having anonaxisymmetric shape (nonaxisymmetric aspheric surface) and an asphericsurface having an axisymmetric shape (axisymmetric aspheric surface) andcooperate with part of the light guide member 10 to form, in the lightguide member 10, an intermediate image corresponding to an imagedisplayed in the image generator 81. In the present embodiment, inparticular, not only is a light-exiting-side lens surface 31 a of thelens surfaces of the first lens 31, which is disposed on the lightexiting side, a nonaxisymmetric aspheric surface but also alight-exiting-side lens surface 33 a of the lens surfaces of the thirdlens 33, which is disposed on the light incident side, is anonaxisymmetric aspheric surface. The first to third lenses 31 to 33,which form the projection lens 30, are accommodated in and supported bythe second image formation main body section 105 b, for example, via alens barrel (see FIGS. 5A and 5B).

The light guide apparatus 20 is formed of the light guide member 10 andthe light transmissive member 50, as described above. Out of the twomembers, the light guide member 10 has a central side (side in front ofeye) that is close to the nose and linearly extends in a plan view. Inthe light guide member 10, the first light guide section 11, which isdisposed on the central side close to the nose, that is, on the lightexiting side, has a first surface S11, a second surface S12, and a thirdsurface S13 as side surfaces having optical functions, and the secondlight guide section 12, which is disposed on the peripheral sideseparate away from the nose, that is, on the light incident side, has afourth surface S14 and a fifth surface S15 as side surfaces havingoptical functions. Among the surfaces described above, the first surfaceS11 and the fourth surface S14 are continuously adjacent to each other,and the third surface S13 and the fifth surface S15 are continuouslyadjacent to each other. The second surface S12 is located between thefirst surface S11 and the third surface S13, and the fourth surface S14and the fifth surface S15 are adjacent to each other with a large angletherebetween. Further, in the embodiment, the first surface S11 and thethird surface S13, which face each other, have planar shapes roughlyparallel to each other. On the other hand, the other surfaces havingoptical functions, that is, the second surface S12, the fourth surfaceS14, and the fifth surface S15 are each a nonaxisymmetric curved surface(free-curved form surface).

The light transmissive member 50 is integrated with and fixed to thelight guide member 10 to form the single light guide apparatus 20 and isa member that assists the light guide member 10 in performing thesee-through function (assistant optical block), as described above. Thelight transmissive member 50 has a first transmissive surface S51, asecond transmissive surface S52, and a third transmissive surface S53 asside surfaces having optical functions. The second transmissive surfaceS52 is located between the first transmissive surface S51 and the thirdtransmissive surface S53. The first transmissive surface S51 is asurface that forms an extension of the first surface S11 of the lightguide member 10. The second transmissive surface S52 is a curved surfacebonded to and integrated with the second surface S12 via an adhesivelayer CC. The third transmissive surface S53 is a surface that forms anextension of the third surface S13 of the light guide member 10. Amongthe surfaces described above, since the second transmissive surface S52and the second surface S12 of the light guide member 10 are bonded toand integrated with each other via the thin adhesive layer CC, the twosurfaces have shapes having roughly the same curvature.

Among the plurality of surfaces that form the light guide member 10, atleast one of the surfaces S14 and S15, which are the surfaces other thanthe first surface S11 to the third surface S13 and free-curved formsurfaces, has at least one point where the sign of curvature varies inaccordance with the direction. The thus formed free-curved form surfaceallows reduction in the size of the light guide member 10 with theguidance of the video image light being precisely controlled.

A main body 10 s of the light guide member 10 has high lighttransmittance in the visible wavelength region and is a unitary part,but the light guide member 10 can be considered as the combination ofthe first light guide section 11 and the second light guide section 12in a functional sense, as described above. The first light guide section11 not only allows the video image light GL to be guided through thelight guide member 10 and exit out thereof but also allows see-throughobservation of outside light HL. The second light guide section 12allows the video image light GL to enter the light guide member 10 andguided therethrough.

In the first light guide section 11, the first surface S11 functions asa refraction surface that causes the video image light GL to exit out ofthe first light guide section 11 and further functions as a totalreflection surface the inner side of which totally reflects the videoimage light GL. The first surface S11 is located in front of the assumedeye position EY (eye EY) and has a planar shape, as described above. Thefirst surface S11 is a surface formed by a hard coat layer 27 coated onthe surface of the main body 10 s.

The second surface S12 is accompanied by a half-silvered mirror layer15, which is formed on a surface of the main body 10 s, and functions asa semi-transmissive/reflective surface (semi-transmissive/reflectivesection) that reflects the video image light GL but transmits theoutside light HL.

The third surface S13 functions as a total reflection surface the innerside of which totally reflects the video image light GL. The thirdsurface S13 is located roughly in front of the eye EY and has a planarshape, as the first surface S11 does. Since the first surface S11 andthe third surface S13 are surfaces parallel to each other, when theviewer views the outside light HL through the first surface S11 and thethird surface S13, the diopter provided by the two surfaces is zero, andno particular change in magnification occurs. The third surface S13 is asurface formed by the hard coat layer 27 coated on the surface of themain body 10 s.

In the second light guide section 12, the fourth surface S14 functionsas a total reflection surface the inner side of which totally reflectsthe video image light GL. The fourth surface S14 further functions as arefraction surface that causes the video image light GL to enter thesecond light guide section 12. That is, the fourth surface S14 has boththe function as the light incident surface that allows the video imagelight GL to externally enter the light guide member 10 and the functionas the light reflection surface that causes the video image light GL topropagate in the light guide member 10. The fourth surface S14 is asurface formed by the hard coat layer 27 coated on the surface of themain body 10 s.

In the second light guide section 12, the fifth surface S15 is formed bydeposition of a light reflection film RM made of an inorganic materialon a surface of the main body 10 s and functions as a reflectionsurface.

The light transmissive member 50 has high light transmittance in thevisible wavelength region, and a main body portion of the lighttransmissive member 50 is made of a material having a refractive indexroughly equal to the refractive index of the main body 10 s of the lightguide member 10. The light transmissive member 50 is formed by bondingthe main body portion to the main body 10 s of the light guide member 10and then depositing a hard coat on the main body portion along with themain body 10 s bonded thereto. That is, the light transmissive member 50has the hard coat layer 27 provided on the surface of the main bodyportion, as the light guide member 10 does. Each of the firsttransmissive surface S51 and the third transmissive surface S53 is asurface formed by the hard coat layer 27 coated on the surface of themain body portion.

The light guide apparatus 20 is formed by bonding the base members thateventually form the light guide member 10 and the light transmissivemember 50 to each other and then depositing a coating on the bonded basemembers in a dip process. That is, the hard coat layer 27 on the lightguide member 10 is provided over the entire light guide apparatus 20along with the light transmissive member 50.

As described above, the video image light from the image generator 81 isguided through the light guide member 10 while reflected five times offthe first surface S11 to the fifth surface S15 including totalreflection at least twice. The light guide operation described above notonly allows display of the video image light GL and visual recognitionof outside light HL in see-through observation at the same time but alsoallows correction of aberrations of the video image light GL.

The optical paths of the video image light GL and other types of lightin the virtual image display apparatus 100 will be described below. Thevideo image light GL having exited from the image display apparatus 80passes through the lenses 31 to 33, which form the projection lens 30and through which the video image light GL converges and receivesintended astigmatism, and is incident on the fourth surface S14, whichis a surface of the light guide member 10 and has positive refractivepower. The astigmatism is canceled out when the video image light GLtravels via the surfaces of the light guide member 10, and video imagelight having an initial state eventually exits toward the viewer's eye.

The video image light GL having been incident on and passed through thefourth surface S14 of the light guide member 10 travels whileconverging, and when the video image light GL travels through the secondlight guide section 12, the video image light GL is reflected off thefifth surface S15, which has relatively small positive refractive power,and is incident on the inner side of the fourth surface S14 again andreflected off the fourth surface S14.

The video image light GL reflected off the fourth surface S14 of thesecond light guide section 12 enters the first light guide section 11,where the video image light GL is incident on and totally reflected offthe third surface S13, which has substantially no refractive power, andis incident on and totally reflected off the first surface S11, whichhas substantially no refractive power.

In this process, the video image light GL forms an intermediate image inthe light guide member 10 before or after the video image light GLtravels via the third surface S13. The image plane of the intermediateimage corresponds to the image plane OI of the image generator 81.

The video image light GL totally reflected off the first surface S11 isincident on the second surface S12. In particular, the video image lightGL incident on the half-silvered mirror layer 15 is partially reflectedoff the half-silvered mirror layer 15, with part of the video imagelight GL passing therethrough, and is incident on the first surface S11again and passes therethrough. The half-silvered mirror layer 15 acts asan optical element having relatively large positive refractive power andaffects the video image light GL reflected off the half-silvered mirrorlayer 15 accordingly. On the other hand, the first surface S11 acts asan optical element having no refractive power and affects the videoimage light GL passing through the first surface S11 accordingly.

The video image light GL having passed through the first surface S11 isincident in the form of a roughly parallelized luminous flux on thepupil of the viewer's eye EY or the position equivalent thereto. Thatis, the video image light GL in the form of a virtual image allows theviewer to view the image formed on the image generator 81.

On the other hand, the outside light HL incident on the light guidemember 10 and in a portion on the +X side of the second surface S12passes through the third surface S13 and the first surface S11 of thefirst light guide section 11. In this process, aberrations and otherdisadvantageous effects hardly occur because the third surface S13 andthe first surface S11 are flat surfaces roughly parallel to each other.That is, the viewer views a distortion-free outside image through thelight guide member 10. Similarly, the outside light HL incident on thelight guide member 10 and in a portion on the −X side of the secondsurface S12, that is, the outside light HL incident on the lighttransmissive member 50 passes through the third transmissive surface S53and the first transmissive surface S51 of the light transmissive member50, and no aberrations or other disadvantageous effects occur becausethe third transmissive surface S53 and the first transmissive surfaceS51 are flat surfaces roughly parallel to each other. That is, theviewer views a distortion-free outside image through the lighttransmissive member 50. Further, the outside light HL incident on thelight transmissive member 50 corresponding to the second surface S12 ofthe light guide member 10 passes through the third transmissive surfaceS53 and the first surface S11, and aberrations and other disadvantageouseffects hardly occur because the third transmissive surface S53 and thefirst surface S11 are flat surfaces roughly parallel to each other. Thatis, the viewer views an outside image with a small amount of distortionthrough the light transmissive member 50. The second surface S12 of thelight guide member 10 and the second transmissive surface S52 of thelight transmissive member 50 have roughly the same curved shape androughly the same refractive index, and the gap between the secondsurface S12 and the second transmissive surface S52 is filled with theadhesive layer CC having a refractive index that is roughly the same asthe refractive indices of the two surfaces. That is, the second surfaceS12 of the light guide member 10 or the second transmissive surface S52of the light transmissive member 50 does not act as a refractive surfacethat affects the outside light HL.

In an optical system of related art in which an intermediate image isformed and total reflection in a light guide member is used to guidelight, such as the optical system described above, to maintain highprecision while attempting reduction in the size of an apparatus inwhich the optical system is incorporated, a free-curved form surface isused in the light guide member or any other optical element to adjustthe optical path with aberrations suppressed. For example, inJP-A-2015-72438, the requirement of size reduction is satisfied withaberrations corrected by providing not only the light guide member butalso part of a projection lens (light-exiting-side lens surface) withfree-curved form surfaces. However, for example, since the totalreflection condition needs to be maintained to guide light in the lightguide member and other constraints are imposed, the size reduction islimited from a design point of view. Specifically, for example, in acase where the distance from the intersection C1 to the intersection C2in the light guide apparatus 20 shown in FIG. 2 is desired to beshortened, that is, the length of the light guide apparatus 20 in thelight guide direction is desired to be shortened, the condition underwhich the video image light is totally reflected tends to be abottleneck. In this case, if the lens surface 33 a is not formed of anonaxisymmetric aspheric surface unlike in the present application, itis possibly particularly difficult to control the sub-pencil of lightGLa, which is a light component that exits from an inner portion of theimage display apparatus 80 or a portion thereof close to the viewer'sbody, in such a way that the sub-pencil of light GLa satisfies the totalreflection condition on the surfaces S11, S13 and S14. For example, itis conceivable to adjust the shape of a portion which forms the surfaceS12 and is close to the surface S13 and via which light components thatare particularly unlikely to satisfy the total reflection conditiontravel in such a way that the sub-pencil of light GLa satisfies thetotal reflection condition. In the adjustment, however, not only doesthe portion that forms the surface S12 and is close to the surface S13need to be adjusted, but also a portion of the surface S12 which extendsfrom the side thereof close to the surface S13 to a central side thereofand which forms the entire segment via which the sub-pencil of light GLatravels needs to be entirely adjusted. In this case, part of theadjusted portion (portion of surface S12 that is close to centerthereof), which is also a segment via which the sub-pencil of light GLbtravels, which is a light component that exits from an outer portion ofthe image display apparatus 80 or a portion thereof separate away fromthe viewer's body, is subject to a variety of constraints in theadjustment of the shape of the surface S12, resulting in a difficulty inaberration correction in the optical system as a whole. Further, asanother candidate of the portion to be adjusted, for example, it isconceivable to adjust the surface S14, which is a nonaxisymmetricaspheric surface and where the sub-pencil of light GLa and thesub-pencil of light GLb are reflected off in regions separate from eachother. The surface S14 is, however, a portion that not only reflects thevideo image light GL but also transmits the video image light GL, and,for example, the region where the sub-pencil of light GLa is reflectedoverlaps with the region where the sub-pencil of light GLb passes. Avariety of constraints are therefore imposed also in the adjustment ofthe surface S14.

In contrast, in the present embodiment, in particular, not only is thelens surface 31 a of the first lens 31 disposed on the light exitingside a nonaxisymmetric aspheric surface, but also the light-exiting-sidelens surface 33 a of the third lens 33 disposed on the light incidentside is a nonaxisymmetric aspheric surface. The lens surface 33 a is alens surface that is one of the lens surfaces of the projection lens 30and located in a position relatively close to the image displayapparatus 80. Therefore, among peripheral regions (called cornerregions) of the image plane OI, the sub-pencils of light GLa and GLb,which exit from two points P1 and P2 in inner and outer corner regionsIA and OA different from each other, pass through the lens surface 33 abefore they intersect each other, as shown, for example, in FIG. 2. Thatis, in the case described above, the lens surface 33 a, which is anonaxisymmetric aspheric surface, is located in a position where thesub-pencils of light GLa and GLb, which are light components that shouldreach the viewer's eye among the pencils of light of the video imagelight that exit from the two points P1 and P2 in the different cornerregions of the image plane OI, which is the light exiting plane of theimage display apparatus 80, do not intersect each other. When the thuslocated lens surface 33 a is a nonaxisymmetric aspheric surface(free-curved form surface), the lens surface 33 a separately affects thesub-pencil of light GLa, which exits from an inner region of the imageplane OI or a region thereof close to the viewer's body, and thesub-pencil of light GLb, which exits from an outer region of the imageplane OI or a region separate away from the viewer's body. That is, forexample, aberration correction performed on the sub-pencil of light GLaand aberration correction performed on the sub-pencil of light GLb canbe separately performed.

As comparison purposes, for example, consider the lens surface 31 a. Inthe position of the lens surface 31 a, since the segment where thesub-pencil of light GLa passes and the segment where the sub-pencil oflight GLb passes overlap with each other, the sub-pencil of light GLaand the sub-pencil of light GLb cannot be separated from each other forseparate aberration correction, but only correction of aberrations ofthe pencil of light as a whole can be performed. In the presentembodiment, in which a nonaxisymmetric aspheric surface (lens surface 33a) is located in a position where the light components that should reachthe viewer's eye (sub-pencils of light GLa and GLb) in the pencil oflight of the video image light do not intersect each other, the size ofthe optical system can be further reduced and hence the size of theentire apparatus can be reduced with a variety of types of opticalprecision, such as the resolution and the angle of view, maintained tobe equal to those of the virtual image display apparatus disclosed, forexample, in JP-A-2015-72438. Specifically, in the light guide apparatus20, for example, the distance (spacing) from the intersection C1 to theintersection C2 can be set at 48 mm or smaller, as described above.

Further, in this case, the overall length of the projection lens 30 canbe shorter than that in related art, and the lens thickness of each ofthe lenses 31 to 33 can be reduced. As a result, further size reductioncan be achieved, whereby a more stylish exterior appearance in anaesthetic sense can be achieved.

Further, in the present embodiment, the sight line axis SX is inclinedwith respect to the lens optical axis LX by 6.7° and inclined withrespect to a normal to the light guide axis DX by about 10°, asdescribed above. Also in this regard, the exterior appearance shape ismade more stylish.

Further, in the present embodiment, the projection lens 30 is configuredto be a complicated off-axis optical system, and the lenses that formthe projection lens 30 are arranged in a relatively packed manner, asdescribed above. Moreover, the light that exits from the image displayapparatus 80 is adjusted in correspondence to the configuration of theprojection lens 30 and the arrangement of the lenses thereof. That is,the exit angles of the sub-pencils of light that exit from the imageplane OI, which is the light exiting plane of the image displayapparatus 80, are asymmetric with respect to the lens optical axis LX,which represents the center of the image display apparatus 80.

The exit angles of the sub-pencils of light that form the video imagelight GL will be more specifically described below with reference toFIGS. 3 and 4. First, consider sub-pencils of light GLa1, GLa2, GLb1,and GLb2, which exit from lower right (inner), upper right (inner),lower left (outer), and upper left (outer) four corners (corner regionsIA1, IA2, OA1, and OA2) of the rectangular region of the image displayapparatus 80, respectively, and FIGS. 3 and 4 show that the exit anglesof the sub-pencils of light GLb1 and GLb2, which exit from the outerregions, are greater than the exit angles of the sub-pencils of lightGLa1 and GLa2, which exit from the inner regions (asymmetry inrightward/leftward direction). Therefore, even in the case where theprojection lens 30 and other components are formed of the complicatedlyshaped optical system described above, luminance unevenness and otherdisadvantageous phenomena in visually recognized video images can besuppressed. On the other hand, FIGS. 3 and 4 show that the exit anglesare equal to each other between the inner regions or the outer regions(symmetry in upward/downward direction). The sub-pencils of light GLa1,GLa2, GLb1, and GLb2 do not intersect one another at the lens surface 33a.

The above discussion will be reviewed from the viewpoint of the firstdirection DD1 and the second direction DD2. Consider the sub-pencils oflight that form the video image light GL in a plane (xy plane) parallelto the image plane OI of the image display apparatus 80. The pencils oflight that exit from the pixels arranged in the first direction DD1,which is the x direction (horizontal direction), exit at different exitangles along the second direction DD2, which is the y direction(vertical direction). Further, in the present embodiment, the curvatureof the lens surface 33 a of the projection lens 30 is changed inaccordance with the position where each sub-pencil of light that exitsfrom the image display apparatus 80 passes. Further, the curvature ofthe lens surface 33 a is changed in correspondence with the incidenceangles of the sub-pencils of light (sub-pencil of light GLa andsub-pencil of light GLb in FIG. 2, for example) at the surface S12 ofthe light guide member 10.

The structure of a stop ST provided in the projection lens 30 will beillustrated and described below with reference to FIGS. 5A and 5B andFIGS. 6A and 6B. FIG. 5A is a cross-sectional view showing an example ofthe configuration of the projection lens 30, and FIG. 5B is a front viewshowing an example of a lens barrel 39, which forms the projection lens30. FIG. 6A conceptually shows the arrangement of the image displayapparatus 80 and the stop ST in the projection lens 30 in the exampleshown in FIGS. 5A and 5B. FIG. 6B conceptually shows a variation of thearrangement of the image display apparatus 80 and the stop ST in theprojection lens 30 and will be described later in detail. In theembodiment, the stop ST is provided as part of the lens barrel 39, asshown in FIG. 5A. The stop ST is so disposed between the second lens 32and the third lens 33 as to be orthogonal to the lens optical axis LX,as shown in FIG. 5A, and the stop ST removes unnecessary light so thatno unwanted light (ghost light) is produced inside and outside of videoimages. The stop ST has a trapezoidal shape in the front view, as shownin FIG. 5B. As a result, in the asymmetric state described above,unnecessary light can be appropriately removed in correspondence withthe sub-pencils of light that exit from the image plan OI.

The shape and structure of the stop ST will be described below in moredetail. In the embodiment, as shown in FIGS. 5A and 5B, it is firstassumed that the x direction is the first direction DD1 and the ydirection is the second direction DD2, as in the above description. Inother words, the first direction DD1 is the direction orthogonal to thedirection of a normal to the image plane OI (Z direction in which lensoptical axis LX in FIG. 2 extends) and corresponding to the light guidedirection (direction in which light guide axis DX in FIG. 2 extends) ofthe light guide member 10 (direction extending in the XZ plane in FIG.2, as the light guide direction extends), and the second direction DD2is the direction orthogonal to both the direction of a normal to theimage plane OI and the first direction DD1. Further, in the embodiment,it is assumed that in the stop ST, a first axis XX1 is an axis thatintersects the lens optical axis LX, which passes through the center ofthe image plane OI, and is parallel to the first direction DD1, and thata second axis XX2 is an axis that intersects the lens optical axis LXand is parallel to the second direction DD2, as shown in FIGS. 5B and6A. In this case, in correspondence with the asymmetry of thesub-pencils of light that form the video image light GL along the firstdirection DD1 and the symmetry of the sub-pencils of light along thesecond direction DD2, an opening OP formed by the stop ST has a shapesymmetric with respect to the first axis XX1 but asymmetric with respectto the second axis XX2. In particular, in the case shown in FIG. 5B, theopening OP has an isosceles trapezoidal shape that spreads symmetricallywith respect to the first axis XX1 from the outer side toward the innerside of the lens barrel 39.

The shape of the stop ST shown in FIGS. 5A and 5B and FIG. 6A ispresented by way of example, and it is conceivable to employ anothershape. For example, as conceptually shown in FIG. 6B, which correspondsto FIG. 6A, when the stop ST is so disposed as to incline with respectto the lens optical axis LX, that is, when the stop ST is disposed in anon-orthogonal arrangement, the shape of the opening appears to be atrapezoid in a front view even in a case where the opening has, forexample, a rectangular shape (oblong shape) instead of a trapezoidalshape. Unnecessary light can be more exactly removed by setting thedegree of inclination of the stop ST with respect to the lens opticalaxis LX in correspondence with the change in the exit angle. In thiscase, the stop ST is not necessarily formed along a non-orthogonal flatplane and may be formed along a curved plane (non-flat plane).

The light that exits from the image display apparatus 80 has anangle/luminance characteristic that greatly depends on the pixel openingshape. In general, the greater the opening shape, the greater the fullvalue half angle of the angle/luminance characteristic, that is, lightof high luminance exits even in a direction inclining by a large anglewith respect to a normal to the panel, and the smaller the openingshape, the smaller the full value half angle, resulting in a peakycharacteristic. In particular, in an ultra-compact display device usedin an HMD, such as the virtual image display apparatus 100 according tothe present embodiment, the size of the opening shape of one pixel issmaller than 10 μm in some cases. In such cases, the luminance in adirection inclining, for example, by about 20° with respect to a normalto the image plane OI is undesirably smaller than 50% of the luminancein the direction of the normal. As a result, luminance unevenness occursin video images in some cases. In particular, in a case where an opticalsystem that causes the state of a pencil of light to vary in accordancewith the on-panel position where the pencil of light exits is employed,as in the present embodiment, luminance unevenness can be a big problem.To avoid the problem, in the present embodiment, the pixel layout is soadjusted that a pixel from which light exits at a larger exit angle hasa larger opening for suppression of occurrence of the luminanceunevenness. In the present embodiment, to allow the adjustment to be somade that the exit angle along the second direction DD2 (y direction)varies in accordance with the position in the first direction DD1 (xdirection), each opening may be so structured as to be, for example,larger in the second direction DD2 than in the first direction DD1, andthe size of the opening of each pixel may be changed in accordance withthe position of the pixel in the first direction DD1. Instead, the panelsubstrate structure can be so configured that the luminance at a certainangle with respect to the direction of a normal to the panel ismaximized. That is, in the pencil of light that exits from the imagedisplay apparatus 80, the direction of a light beam that exits from apixel and has the highest luminance varies in accordance with theposition of the pixel in the image display apparatus 80.

A more specific example of the optical configuration of the imagedisplay apparatus 80 of the virtual image display apparatus 100 will bedescribed below in detail with reference to FIGS. 7A and 7B.

First, the image display apparatus 80 is a self-luminous image displayapparatus including not only the image generator 81 and the color filterlayer CF, which is disposed as the light orientation controller 82 in aposition immediately downstream of the image generator 81, but also thedrive controller (not shown) that controls the action of the imagegenerator 81, as described above. An example of the configuration of theimage display apparatus 80 will be more specifically described withreference to FIGS. 7A and 7B. The image generator 81 of the imagedisplay apparatus 80 includes a plurality of transparent electrodes(anodes) 71 a, which are pixel electrodes, a counter electrode (cathode)72 a, an organic EL layer 73 a, which is disposed between thetransparent electrodes 71 a and the counter electrode 72 a and serves asa light emission functional layer (light emitting layer), and aprotective layer 74 a. The color filter layer CF as the lightorientation controller 82 is formed on the protective layer 74 a. Thecolor filter layer CF is formed of color filter sections CFr, CFg, andCFb for red, green and blue, and the color filter sections CFr, CFg, andCFb for the three colors are arranged in a matrix in correspondence withthe plurality of transparent electrodes (anodes) 71 a, which are pixelelectrodes. In the thus configured image display apparatus 80, theelectrodes 71 a and 72 a are caused to operate as appropriate to allowthe organic EL layer 73 a to emit light, whereby the image generator 81outputs the video image light GL from the image plane OI. That is, theimage display apparatus 80, which includes the organic EL device as alight source, emits the video image light GL from each of the pixelsthat form the image plane OI. Further, when the light emitted by theimage generator 81 passes as the video image light GL through the colorfilter layer CF, the image display apparatus 80 outputs color videoimage light (image light) GL. In the present embodiment, in the colorfilter layer CF as the light orientation controller 82, the color filtersections CFr, CFg, and CFb for the three colors are so arranged that theinterval therebetween differs from the interval between thematrix-arrangement pixels that form the image plane OI, that is, theinterval between the plurality of matrix-arrangement transparentelectrodes 71 a, 71 a, 71 a. As a result, the positions of the colorfilter sections CFr, CFg, and CFb for the three colors are shifted fromthe positions of the corresponding electrodes 71 a, 71 a, 71 a in theperiphery of the image generator 81 that is separate from the lensoptical axis LX, which is the central optical axis of the image displayapparatus 80, as shown in FIG. 7A (in FIG. 7A, the positions of thecolor filter sections CFr, CFg, and CFb for the three colors are shiftedrightward, or the positions of the outer edges of the color filtersections are shifted from the positions of the electrodes), whereby theorientation of the light components that exit through the color filterlayer CF inclines in an oblique direction (diagonally right direction inFIG. 7A), and the light components therefore so exit as to approach thelens optical axis LX. On the other hand, in the vicinity of the lensoptical axis LX of the image display apparatus 80, that is, in a centralportion of the image display apparatus 80, the shift described abovedoes not occur or the amount of the shift is small if any, whereby theorientation of the exiting light components does not incline, and thelight components exit vertically or roughly vertically. Adjusting thedegree of the inclination of the exiting light on a position basis or ona certain-area-region basis allows a desired light exiting state(asymmetric state) to be achieved.

The above description as a whole can be expressed differently asfollows: In the image display apparatus 80, the image generator 81 is apixel matrix formed by arranging pixels in a matrix in the form of theplurality of transparent electrodes 71 a, which are pixel electrodes, inthe image plane OI; and the color filter layer CF as the lightorientation controller 82 has a shape that varies in accordance with theposition in the image plane OI in such a way that the interval betweenthe color filter sections is shifted from the interval between thematrix-arrangement pixels that form the image plane OI (interval betweentransparent electrodes 71 a) by a value that increases with distancefrom the center toward the periphery of the color filter layer CF. Theconfiguration described above allows control of the light orientationstate to be optimized for each position in the image plane OI. That is,in the light that exits from each position in the image plane OI, alight beam that exits at an angle corresponding to a principal ray ofthe light is maximized in terms of optical intensity. As a result, thecolor filter layer CF as the light orientation controller 82 controlsthe light component that exits from each position in the image plane OIin such a way that the exiting light has an intensity distribution inwhich the intensity is maximized in the axial direction of the principalray of the light. As described above, in the present embodiment, thecolor filter layer CF functions as the light orientation controller 82,which controls the orientation of the video image light GL, which is theexiting light.

As described above, in the projection lens 30 of the virtual imagedisplay apparatus 100 according to the present embodiment, the lenssurface 33 a, which is located in a position where light components thatshould reach the viewer's eye in the pencil of light of the video imagelight that exits from each of the two points P1 and P2 in the differentcorner regions IA and OA in the image plane OI, which is the lightexiting plane of the image display apparatus 80, do not intersect oneanother, is a nonaxisymmetric aspheric surface, whereby the size of theoptical system can be further reduced and the size of the overallapparatus can therefore be reduced with a variety of types of opticalprecision, such as the resolution and angle of view, maintained.

FIG. 8 is a conceptual view for describing a variation of the imagedisplay apparatus 80 and corresponds to FIG. 7A. In the variation shownin FIG. 8, a microlens array MLA is disposed on the color filter layerCF. In the present variation, the microlens array MLA functions as thelight orientation controller 82, or the microlens array MLA cooperateswith the color filter layer CF to function as the light orientationcontroller 82. Specifically, a plurality of element lenses EL, whichform the microlens array MLA, are arranged in a matrix in correspondencewith the color filter sections CFr, CFg, and CFb for the three colors,and the shapes of the element lenses EL are non-uniformly configuredwith respect to the pixel arrangement and in accordance with thepositions where the color filter sections CFr, CFg, and CFb for thethree colors are disposed, that is, the positions of thematrix-arrangement pixels that form the image plane OI (positions ofelectrodes 71 a). Specifically, for example, the outer shapes of theelement lenses EL differ from one another, the positions of the elementlenses EL are so arranged as to be shifted from the positions of thecorresponding pixels, or the microlens array MLA is so arranged that theinterval between the microlenses is smaller than the interval betweenthe pixels. As a result, the microlens array MLA alone or the microlensarray MLA that cooperates with the color filter layer CF functions asthe light orientation controller 82, which adjusts the light componentsthat form the video image light GL. In other words, the microlens arrayMLA functions as a deflection member that changes the angle of exitinglight.

Others

The invention has been described above with reference to the embodiment,but the invention is not limited to the embodiment described above andcan be implemented in a variety of other aspects to the extent that theydo not depart from the substance of the invention. For example, theabove description has been made of a see-through virtual image displayapparatus, and the structure shown in the present embodiment can be usedin a non-see-through-type virtual image display apparatus.

In the above description, the image generator 81 including an OLED(organic EL) is used as the image display apparatus (video device) 80,but not necessarily, and the image display apparatus 80 can be formed ofa transmissive liquid crystal display device and a backlight, or any ofa variety of other components can be used to form the image displayapparatus 80.

FIG. 9 is a conceptual view for describing another variation of theimage display apparatus. In an image display apparatus 180 according tothe variation shown in FIG. 9, a transmissive liquid crystal displaydevice is used, and an image generator 181 is formed of a liquid crystalpanel and includes a TFT pixel structure and a black matrix structure.That is, a pair of transparent electrodes 171 a and 171 b and a pair oforientation films 172 a and 172 b sandwich a liquid crystal layer 173 awith the color filter layer CF provided, and light radiated from abacklight BL, which is light source light, is modulated. In thisconfiguration, a black matrix BM is provided between the color filtersections CFr, CFg, and CFb for the three colors, which form the colorfilter layer CF. In the present variation, the shape of the black matrixBM is changed in accordance with the positions where the color filtersections CFr, CFg, and CFb for the three colors are disposed, that is,the positions of the matrix-arrangement pixels that form the image planeOI (positions of electrodes 171 a), and the configuration describedabove is allowed to function as the light orientation controller 82,which adjusts the light components that form the video image light GL.The structure described above can be expressed in another way asfollows: The interval in the TFT pixel structure differs from theinterval in a counter substrate pixel structure having the black matrixstructure.

Further, for example, a configuration using a reflective liquid crystaldisplay device is conceivable, and a digital micromirror device or anyother similar device can be used in place of the image generator 81formed, for example, of a liquid crystal display device. An LED arraycan, for example, be used as the self-luminous element.

In the embodiment described above, the panel-type image displayapparatus 80 including an OLED (organic EL) is used, and a sweep-typeimage display apparatus can be used in place of the panel-type imagedisplay apparatus 80. Specifically, for example, a light diffusionelement may be disposed in the image plane OI, and a sweep-typeillumination system may be used to sweep light in the position of theimage plane OI to form an image, which may be allowed to exit in theform of video image light on the basis of the diffusion effect of thelight diffusion element. The same configuration described in theembodiment can be used with the sweep-type image display apparatus.

In the embodiment described above, the right and left light guideapparatus 20 are separately manufactured, but not necessarily, forexample, a configuration in which the light transmissive member isshared can be employed. FIGS. 10A and 10B are conceptual views fordescribing a variation of the light guide apparatus. In this example, apair of right and left light guide members 10, 10 and a lighttransmissive member 150 form a unitary optical member in which the pairof right and left light guide members 10, 10 sandwich the single lighttransmissive member 150 so as to be connected to each other and whichfunctions as a light guide apparatus 20 that is a unitary apparatus fromright to left. In this case, the light transmissive member 150 allowspositioning for binocular vision to be readily and precisely performed.For example, bending the light transmissive member 150 at a centralsection CE by an appropriate amount allows the right and left angles tobe specified, as shown in FIG. 10A. Further, providing recessed sectionsCVa and CVb in the upper and lower ends in the central section CE, asshown in FIG. 10B, allows the recessed sections CVa and CVb to be usednot only in positioning (position fixing) for bonding and fixing thelight guide members 10, 10 to the light transmissive member 150 in amanufacturing step but also as a location for providing the nosereceiver.

In the above description, the sections of the light guide apparatus 20that range from the light incident section (second light guide section12) to the light exiting section (first light guide section 11) areformed of a single member. Instead of the configuration described above,for example, the video image light GL may be caused to directly enter atotal-reflection-based light guide section without causing the videoimage light GL to travel via a light reflection surface formed, forexample, of the light reflection film RM (see FIG. 2), as shown in FIG.11A, or the light guide member 10 of the light guide apparatus 20 may bedivided into a light incident section 10 p and a light guide section 10q, each of which is formed, for example, of a prism, as shown in FIG.11B. Further, regarding the total reflection, only one of surfaces ofthe light guide section that face each other and extend is involved inthe total reflection but the other surface is not before the light isextracted, as shown in FIGS. 11A and 11B.

In the above description, the projection lens 30, which is formed of aplurality of lenses, is employed as the projection system, but notnecessarily, and a projection prism system 230, which is formed of aprism-shaped member, may be used to form the projection system, as shownin FIG. 12. In this case as well, for example, among surfaces 231 a to233 a, which contribute to optical path deflection in the projectionprism system 230, the light incident surface 233 a, which is located ina position where in the pencil of light of the video image light thatexits from the image display apparatus 80, the sub-pencils of light GLaand GLb, which are light components that should reach the viewer's eye,do not intersect each other, is a nonaxisymmetric aspheric surface(free-curved form surface) for appropriate aberration correction. It isnoted that the reflection surface 232 a and/or the light exiting surface231 a, which are surfaces other than the light incident surface 233 a,may also be a nonaxisymmetric aspheric surface (free-curved formsurface). Further, in FIG. 12, the projection prism system 230, which isthe projection system, and the light guide apparatus 20 (light guidemember 10) are not connected to each other but are separate members.Instead, the projection prism system 230 and the light guide apparatus20 (light guide member 10) can be connected to each other to form aunitary member.

Further, for example, in the lens barrel 39, the stop ST may have anoblong shape (oblong shape elongated in X direction), as shown as avariation in FIGS. 13A and 13B. For example, depending on the length,the shape, and other factors of the light guide member 10 (see FIG. 2and other figures), the stop ST does not necessarily have a trapezoidalshape, unlike the case described with reference to FIG. 5B, and, forexample, unnecessary light can be appropriately removed incorrespondence with the sub-pencils of light.

In the above description, the half-silvered mirror layer(semi-transmissive/reflective film) 15 is formed in a horizontallyelongated rectangular region. Instead, the contour of the half-silveredmirror layer 15 can be changed as appropriate in accordance with theapplication and other specifications of the apparatus. The transmittanceand reflectance of the half-silvered mirror layer 15 can also be changedin accordance with the application and other factors of the apparatus.

The above description has been made of the virtual image displayapparatus 100 including the pair of display apparatus 100A and 100B. Thevirtual image display apparatus 100 can instead be formed of a singledisplay apparatus. That is, instead of providing the set of theprojection/see-through apparatus 70 and the image display apparatus 80in correspondence with each of the right and left eyes, only one of theright and left eyes may be provided with the projection/see-throughapparatus 70 and the image display apparatus 80 for monocular vision ofan image.

In the above description, the half-silvered mirror layer 15 is a simplesemi-transmissive film (dielectric multilayer film). The half-silveredmirror layer 15 can be replaced with a planar or curved hologramelement. Still instead, the half-silvered mirror layer 15 can bereplaced with an optical element having a plurality of minute reflectionsurfaces arranged on a curved surface, a Fresnel mirror, or any otherdiffraction element.

In the above description, the light guide member 10 and other componentsextend in the horizontal direction along which the eyes EY are arranged.The light guide member 10 may instead be so disposed as to extend in thevertical direction. In this case, the light guide member 10 has aparallel arrangement structure instead of the serial arrangementstructure.

The entire disclosure of Japanese Patent Application No. 2015-247051,filed Dec. 18, 2015 is expressly incorporated by reference herein.

What is claimed is:
 1. A virtual image display apparatus comprising: a video device that generates video image light; a light guide member that guides the video image light from the video device based on total reflection that occurs at a plurality of surfaces including a nonaxisymmetric curved surface and serves as part of an optical system to form an intermediate image in the light guide member; and a projection system that causes the video image light from the video device to enter the light guide member, wherein the projection system includes at least one nonaxisymmetric aspheric surface, and the one nonaxisymmetric aspheric surface is located in a position where in a pencil of light of video image light that exits from each of two points in different corner regions of a light exiting plane of the video device, light components that should reach a viewer's eyes do not intersect each other.
 2. The virtual image display apparatus according to claim 1, wherein the video device generates the video image light from a rectangular region, and in the projection system, the one nonaxisymmetric aspheric surface is located in a position where in a pencil of light of video image light that exits from each of four corners of the rectangular region of the video device, light components that should reach the viewer's eyes do not intersect each other.
 3. The virtual image display apparatus according to claim 1, wherein the light guide member has at least two nonaxisymmetric curved surfaces, among the plurality of surfaces that form the light guide member, a first surface and a third surface are so located as to face each other, and the first surface and the third surface provide diopter of roughly zero when an outside scene is visually recognized through the first surface and the third surface, and the video image light from the video device is totally reflected off the third surface, is totally reflected off the first surface, is reflected off a second surface, then passes through the first surface, and reaches an observation side.
 4. The virtual image display apparatus according to claim 1, wherein an exit angle of a pencil of light of the video image light that exits from the video device is asymmetric with respect to a center of the video device.
 5. The virtual image display apparatus according to claim 1, wherein assuming that a first direction is a direction orthogonal to a direction of a normal to the light exiting plane of the video device and corresponding to a light guide direction of the light guide member and that a second direction is a direction orthogonal to the direction of the normal and the first direction, pencils of light that exit from pixels arranged along the first direction in the video device exit at angles difference from one another along the second direction.
 6. The virtual image display apparatus according to claim 5, wherein the projection system has a stop that forms an opening that is not only so located as to be orthogonal to a lens optical axis passing through a center of the video device and parallel to the direction of the normal but also symmetric with respect to a first axis that extends in parallel to the first direction and intersects the lens optical axis but asymmetric with respect to a second axis that extends in parallel to the second direction and intersects the lens optical axis or an opening that is so disposed as not to be orthogonal to the lens optical axis.
 7. The virtual image display apparatus according to claim 5, wherein each of the pixels of the video device is so structured as to spread wider in the second direction than in the first direction.
 8. The virtual image display apparatus according to claim 1, wherein curvature of the one nonaxisymmetric aspheric surface, which forms the projection system, in each position where a pencil of light that exits from the video device passes changes in correspondence with an incidence angle of the pencil of light, which exits from the video device, at the nonaxisymmetric curved surface that forms the light guide member.
 9. The virtual image display apparatus according to claim 1, wherein in a pencil of light that exits from each pixel of the video device, a direction of a light beam having highest luminance varies in accordance with a position of the pixel of the video device.
 10. The virtual image display apparatus according to claim 1, wherein the video device includes a liquid crystal panel, and an interval in a TFT pixel structure differs from an interval in a counter substrate pixel structure having a black matrix structure.
 11. The virtual image display apparatus according to claim 1, wherein the video device includes an organic EL panel that has a light emitting layer and a color filter layer, and an interval in the light emitting layer differs from an interval in the color filter layer.
 12. The virtual image display apparatus according to claim 1, wherein the video device includes a deflection member that is disposed in a light exiting section disposed on a light exiting side, and the deflection member changes the angle of the light.
 13. The virtual image display apparatus according to claim 1, wherein the nonaxisymmetric curved surface of the light guide member is provided at least on a light incident section disposed on a light incident side and a light exiting section disposed on a light exiting side.
 14. The virtual image display apparatus according to claim 1, wherein in the light guide member, a distance from an intersection of a light incident section disposed on a light incident side and a lens optical axis of the projection system to an intersection of a light exiting section disposed on a light exiting side and a sight line axis assumed to be a reference of the viewer's line of sight is 48 mm or smaller.
 15. The virtual image display apparatus according to claim 1, wherein the light guide member has a semi-transmissive/reflective section that partially reflects and transmits the video image light from the video device and outside light, and the light guide member is connected to a light transmissive member via the semi-transmissive/reflective section.
 16. The virtual image display apparatus according to claim 15, wherein the light guide member is formed of a pair of right and left light guide members, and the pair of right and left light guide members and the light transmissive member are so configured that the pair of right and left light guide members sandwich the light transmissive member and are connected each other via the light transmissive member to form a unitary optical member. 